The present disclosure relates generally to a power controller that provides open-circuit protection when an open circuit occurs in a power supply.
Power supply is almost a need for each of consumer electronics, to convert for example power from a power distribution grid into a power voltage or current source specifically required by a core circuit of an electric device. As power supplies are operating in proximity to people, regulations or laws normally require them to equip with protection mechanisms that prevent hazards from happening during abnormal conditions or environments.
Open-circuit and short-circuit tests, mimicking abnormal conditions or environments, are standard test procedures for each device on a printed circuit board (PCB) of a power supply, and a power supply presumably passes these tests if it does not cause any harmful consequences. These tests are preformed when a PCB is powered. Short-circuit test over a resistor on a PCB, for example, suddenly shorts the two ends of the resistor together, equivalently making the resistance of the resistor zero. Open-circuit test for the same resistor separates one of the two ends from the PCB, seemingly like the resistor is not properly soldered thereon.
An auxiliary winding of a power supply could cause output regulation out of control if it is not well soldered. A power controller using primary-side regulation (PSR) monitors and regulates output voltage in the secondary side by detecting a winding voltage at an end of the auxiliary winding in the primary side. If one end of the auxiliary winding that should short to input ground is wrongly disconnected from the input ground, waveform of the winding voltage deforms and the power controller will provide to its control loop wrong information, upon on which the output voltage could be regulated at an over-high voltage level, causing damage to electric apparatus powered by the output voltage.